The present invention is generally related to washing machines and, more particularly, to a system and method for detecting and interrupting an out-of-balance (OOB) condition which can arise during the operation of the washing machine.
In a typical washing machine (such as a top or front-loading washing machine) the OOB condition can actually occur during a spin cycle, for example, when the articles to be cleansed, such as clothing and the like, bunch up asymmetrically at various locations in the basket for holding such articles. For various detrimental reasons the OOB condition is not desirable if left uninterrupted. For example, a tub which encloses the basket may violently strike the cabinet of the washing machine and thus cause damage either to the tub, the cabinet or both. Further, unacceptable stress forces can develop during the OOB condition that can affect the suspension mechanism of the washing machine as well as other components thereof such as the transmission or other suitable connecting device which links the motor of the washing machine to the spinning basket.
Some existing electromechanically controlled washing machines incorporate an OOB switch or combination of a lid and OOB switch which in either case deenergize the motor of the washing machine during high speed spin if the lateral excursion of the outer tub reaches a point where the tub mechanically trips the OOB switch. A drawback of this approach is that a single lateral excursion of the outer tub is sufficient to trip the OOB switch. This is not desirable because the operation of the washing machine can be mistakenly interrupted during situations which do not correspond to an actual OOB condition (i.e., a detrimental or harmful OOB condition), and thus the time required to complete the washing operation increases unnecessarily. For example, as the basket gradually increases its spin speed from a no spin state up to its specified operating spin speed, it is typical to encounter certain natural mechanical frequencies which can induce brief or momentary excursions of the tub. However, such brief or momentary excursions which do not correspond to the actual OOB condition can be sufficient to trip the OOB switch and thus this approach is prone to error being that a single excursion of the tub is all that is required to mechanically trip the OOB switch.
Other washing machines which incorporate a respective microprocessor to provide electronic control of the washing operation can detect the OOB condition and take suitable corrective action to interrupt the OOB condition. However, the OOB detection technique utilized in this approach is implemented through the use of elaborate logic which cooperates with the controlling microprocessor or other such electronic device to detect the OOB condition and thus implementation of this technique which requires use of such elaborate logic adds to the complexity as well as to the cost of the washing machine.
It is therefore an object of the present invention to provide an improved system and method for detecting and interrupting an OOB condition in a washing machine which is not subject to the foregoing disadvantages of existing OOB switches.
It is another object of the present invention to provide a system and method for detecting and interrupting an OOB condition which can be conveniently used either in electronically or electromechanically controlled washing machines.
It is yet another object of the present invention to provide a system and method which does not require elaborate logic to detect and interrupt an OOB condition.